Amended lawsuits have been filed in U.S. District Courts in four cities claiming use of midazolam hydrochloride as the first drug in the three-drug mix leaves the condemned at risk for severe pain during an execution.

Florida used the new mix during the execution of William Happ on Oct. 15. It was the first time it was used in an execution and Happ didn't file any appeals challenging its use.

The seven inmates challenging the use had already sued to stop the previous mix of drugs Florida was using before the change. The filings this week seek to amend the original suits to reflect the new procedure.